Systems, methods, and devices for wind-responsive operation of sun-tracking assemblies

ABSTRACT

The present disclosure relates to operating sun-tracking assemblies in response to one or more wind parameters or conditions. By judiciously reorienting one or more sun-tracking assemblies in response to detected or predicted wind conditions, the potential for wind- damage may be reduced. Some of the sun-tracking assemblies may act as a wind buffer for more fragile or sensitive components, thereby protecting them from damage. Such wind- sensitive components may be other sun-tracking assemblies arranged downwind from the reoriented assemblies. The downwind sun-tracking assemblies may continue to operate normally or substantially normally (i.e., to track the sun) despite the presence of the wind. During times of reduced or no wind, the sun-tracking assemblies may continue to track the sun until wind conditions require reorientation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional Application No. 61/367,550, filed Jul. 26, 2010, which is hereby incorporated by reference herein in its entirety.

FIELD

The present disclosure relates generally to sun-tracking assemblies, and, more particularly, to systems, methods, and devices for arranging and operating sun-tracking assemblies in response to wind.

SUMMARY

Embodiments of the present disclosure relate to operating sun-tracking assemblies in response to one or more wind parameters or conditions. By judiciously reorienting one or more sun-tracking assemblies in response to detected or predicted wind conditions, the potential for wind-damage may be reduced. In particular, some of the sun-tracking assemblies may serve to buffer wind-sensitive components from the wind, thereby protecting them from damage. Such wind-sensitive components may be other sun-tracking assemblies arranged downwind from the reoriented assemblies. The downwind sun-tracking assemblies may continue to operate normally or substantially normally (i.e., to track the sun) despite the presence of the wind. Embodiments of the disclosed subject matter may thus obviate the need to universally deploy wind-sturdy sun-tracking apparatuses and/or to deploy a wind fence.

In one or more embodiments, a method of operating a plurality of sun-tracking assemblies can include, at a first time, moving the plurality of sun-tracking assemblies along respective solar tracking paths so as to follow a movement of the sun. At a second time, a first one of the plurality of sun-tracking assemblies can be redirected away from its respective solar tracking path responsively to a wind condition. Also at the second time, a second one of the plurality of sun-tracking assemblies can continue to be moved along its respective solar tracking path so as to follow the movement of the sun.

In one or more embodiments, a method of operating a field of sun-tracking assemblies can include reorienting a first portion of the field of sun-tracking assemblies away from respective solar tracking paths so as to buffer a second portion of the field from wind such that the second portion of the field can continue following their respective solar tracking paths.

In one or more embodiments, a sun-tracking system can include a field of sun-tracking assemblies, a wind monitoring module, and a control system. The wind monitoring module can be configured to detect or predict a wind condition. The wind condition can include at least one of wind speed, wind direction, and changes in wind speed or wind direction. The control system can be coupled to the wind monitoring module so as to receive a signal therefrom indicative of the wind condition. The control system can also be coupled to the field of sun-tracking assemblies to direct orientations thereof. The control system can be configured to control orientations of the sun-tracking assemblies in a first portion of the field responsively to the wind condition signal and to control orientations of the sun-tracking assemblies in a second portion of the field responsively to a location of the sun.

Objects and advantages of embodiments of the disclosed subject matter will become apparent from the following description when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will hereinafter be described with reference to the accompanying drawings, which have not necessarily been drawn to scale. Where applicable, some features may not be illustrated to assist in the illustration and description of underlying features.

Throughout the figures, like reference numerals denote like elements.

FIG. 1 shows a solar power tower system, according to one or more embodiments of the disclosed subject matter.

FIG. 2 shows another solar power tower system with secondary reflector, according to one or more embodiments of the disclosed subject matter.

FIG. 3 shows a solar power tower system including multiple towers, according to one or more embodiments of the disclosed subject matter.

FIG. 4 shows a solar power tower system including multiple receivers in a single tower, according to one or more embodiments of the disclosed subject matter.

FIG. 5 is a schematic diagram of a heliostat control system, according to one or more embodiments of the disclosed subject matter.

FIG. 6 is a profile view of a heliostat reflector, according to one or more embodiments of the disclosed subject matter.

FIG. 7 is a backside isometric view of components of a heliostat reflector, according to one or more embodiments of the disclosed subject matter.

FIG. 8 is a backside isometric view of components of another heliostat reflector, according to one or more embodiments of the disclosed subject matter.

FIG. 9 is a picture of a single mirror heliostat, according to one or more embodiments of the disclosed subject matter.

FIG. 10 is a picture of a dual mirror heliostat, according to one or more embodiments of the disclosed subject matter.

FIG. 11 shows orientations of heliostats in a solar field surrounding a solar tower, according to one or more embodiments of the disclosed subject matter.

FIG. 12 is a close-up view of one of the heliostats showing various orientations thereof, according to one or more embodiments of the disclosed subject matter.

FIG. 13 shows wind-buffering orientations of heliostats in a solar field, according to one or more embodiments of the disclosed subject matter.

FIG. 14A is a simplified top view of some of the heliostats in a solar field during wind-buffering mode, according to one or more embodiments of the disclosed subject matter.

FIG. 14B shows azimuth orientations of wind-buffering heliostats, according to one or more embodiments of the disclosed subject matter.

FIG. 15 is an aerial view of a solar field of heliostats showing selected wind-buffering portions of the solar field, according to one or more embodiments of the disclosed subject matter.

FIG. 16 is an aerial view of another solar field showing selected wind-buffering portions, according to one or more embodiments of the disclosed subject matter.

FIG. 17 is a photograph of a field of photovoltaic cell sun-tracking assemblies, according to one or more embodiments of the disclosed subject matter.

FIG. 18 is an aerial view of a field of sun-tracking assemblies illustrating selection of wind-buffering assemblies for protecting a component in the field based on wind conditions, according to one or more embodiments of the disclosed subject matter.

FIG. 19 is a schematic diagram of sun-tracking assembly control and inputs, according to one or more embodiments of the disclosed subject matter.

FIG. 20 shows wind-buffering heliostats protecting components within a solar field, according to one or more embodiments of the disclosed subject matter.

DETAILED DESCRIPTION

Orientation of one or more sun-tracking assemblies or devices can be modified from their normal sun-tracking orientation in response to a detected or predicted wind-parameter or condition. For example, one or more sun-tracking assemblies can be reoriented to protect other sun-tracking assemblies from wind, or at least substantially reduce the impact or severity of the wind on the other sun-tracking assemblies. By judiciously reorienting one or more sun-tracking assemblies in response to detected or predicted wind conditions, the potential for wind-damage may be reduced and/or others of the sun-tracking assemblies may be allowed to operate normally or substantially normally (i.e., to track the sun) despite the presence of the wind. Embodiments of the disclosed subject matter may thus obviate the need to universally deploy wind-sturdy sun-tracking apparatuses and/or to deploy a wind fence.

Embodiments of the disclosed subject matter may increase the efficiency for an overall field of sun-tracking devices (as opposed to individual or smaller clusters of devices) at which useful energy is obtained from insolation. Alternatively or additionally, embodiments of the disclosed subject matter may allow for reduced capital requirements for constructing and deploying the sun-tracking devices. For example, sun-tracking assemblies can include, but are not limited, to sun-tracking reflection assemblies (including one or more flat mirrors and/or one or more curved mirror assemblies having one or more focus points) and sun-tracking photovoltaic (PV) assemblies, such as PV panels.

Wind conditions can be measured (for example, by an anemometer located proximal to the sun-tracking apparatuses) or predicted (for example, based on historical data or weather conditions). The wind conditions can be used, for example, by a control system to determine orientations for one or more sun-tracking apparatus that would reduce downwind velocity and/or potential negative impact on other sun-tracking apparatuses or other fragile components. Wind conditions can include, but are not limited to, wind speed, changes in wind speed, wind direction, and changes in wind direction. For example, an increase or decrease in wind speed may trigger a specific orientation-related behavior of one or more sun-tracking devices. In another example, wind direction is monitored relative to deployment geometry for the sun-tracking devices. In yet another example, a change (absolute, relative, or fractional) in wind direction is used to determine orientations.

Wind conditions/parameters can also be used to determine which sun-tracking apparatuses are to be reoriented to account for the wind. For example, sun-tracking apparatuses may be arranged in a solar field divided into quadrants centered at the center of the solar field (or centered with respect to a component/structure to be protected). Sun-tracking apparatuses in one or more quadrants (or portions of the one or more quadrants) may be selected for reorientation to protect other apparatuses or components from the wind. In particular, the quadrant (or quadrants) that are facing the wind may be selected. Determination if a quadrant (or quadrants) is facing the wind can be based on wind direction, wind speed, and the change of the wind direction.

At times, reorientation of one or more sun-tracking assemblies may not be necessary to address current wind conditions. For example, if there is no wind or if the wind is present at relatively low velocity, sun-tracking assemblies may continue to track the sun without requiring reorientation. In embodiments, a threshold value may be employed for one or more wind conditions, e.g., wind speed, wind direction, and/or wind acceleration (magnitude and/or direction). When the threshold value is exceeded (e.g., when the wind speed exceeds a minimum threshold velocity) one or more designated sun-tracking assemblies that were operating in some sort of insolation harvesting (or sun-tracking) mode may be reoriented to a wind-protective mode. The wind-protective (or wind-buffering) mode may result in significantly less insolation harvest or even no insolation harvest therefrom. For example, after reorientation the rate of insolation harvest may drop by at least 50%, by at least 70%, or by at least 90%. Thus, one or more solar-tracking assemblies can be temporarily sacrificed, at least with regard to insolation harvesting, in order to maintain useful operation of other solar-tracking assemblies during certain wind conditions.

Wind mode orientation for one or more sun-tracking assemblies can be selected so as to facilitate operation of other sun-tracking assemblies within the solar field. In addition, certain sun-tracking assemblies may be selected for wind mode orientation based on their location with respect to other sun-tracking assemblies (or other fragile components) and/or construction of the sun-tracking assemblies (e.g., if the assembly has a more sturdy or wind-resistant construction than other assemblies). For example, one or more perimeter or relatively outer sun-tracking assemblies may adopt intelligently selected orientations that reduce a magnitude of wind incident upon other sun-tracking assemblies (for example, downwind or relatively inner sun-tracking assemblies). The intelligently selected orientations may be based on fluid mechanic analysis or computational fluid dynamic (CFD) models. The perimeter assemblies may thus shield or buffer the inner assemblies from the wind, thereby improving operating conditions for the inner assemblies.

Multiple perimeter assemblies and their wind mode orientations may be selected to enhance the buffer effect. For example, the wind mode orientations of a plurality of assemblies may be chosen relative to each other to at least partially blocking incoming wind. The orientations of panels of the assemblies may have a staggered appearance, for example in the direction of the wind in an aerial view or in a direction from a center to the perimeter of the field of assemblies in an aerial view.

After reorienting to wind mode operation, the assemblies may remain in the new orientation (or in an orientation proximal to the new orientation) for a given period of time. For example, the assemblies may remain in the new orientation for at least 1.5 times as long as the transit time from the normal operating orientation to the wind mode orientation. If wind conditions abate, the assemblies may return to normal operating mode, i.e., tracking the sun to harvest insolation, either by reflection or photovoltaic conversion. As compared to the normal operating mode, the reorienting may involve modifying the elevation angle and/or azimuth angle of a panel (e.g., mirror or PV panel) of the sun-tracking assembly by at least 10°, for example, between 10° and 80°. For example, an elevation angle of the reoriented assembly panel may be between 20° and 70° above the horizon. In another example, the reorienting may include rotation away from or toward the horizon based on a detected or predicted increase in wind speed.

As noted above, sturdier or more wind resistant sun-tracking devices may be used for the wind mode orientations to buffer or protect other sun-tracking devices from the wind, thereby allowing other sun-tracking devices to be less sturdy or wind resistant. Thus, more expensive sun-tracking devices that are better reinforced against the wind and/or include heavier, stronger, or thicker materials and/or are generally more sturdy can be deployed in regions of the solar field to protect other sun-tracking devices, which may be relatively weaker, cheaper, and or less sturdy. For example, the perimeter of the solar field can include the more sturdy sun-tracking devices while the inner locations away from the perimeter region can include less sturdy sun-tracking devices. Sturdiness or ruggedness of the sun-tracking device may be a function of the distance of the device from the perimeter of the cluster or field, with devices closer to the perimeter having increased strength or wind resistance.

Embodiments of solar tower systems are shown in FIGS. 1-4. In embodiments, incident solar radiation can be used by the solar tower systems to generate solar steam and/or for heating molten salt. In FIG. 1, a solar tower system can include a solar tower 50 that receives reflected focused sunlight 10 from a solar field 60 of heliostats (individual heliostats 70 are illustrated in the left-hand portion of FIG. 1 only). For example, the solar tower 50 can have a height of at least 25 meters, at least 50 meters, at least 75 meters, or even higher. The heliostats 70 can be aimed at solar energy receiver system 500, for example, a solar energy receiving surface of one or more receivers of system 500. Heliostats 70 can adjust their orientation to track the sun as it moves across the sky, thereby continuing to reflect sunlight onto one or more aiming points associated with the solar energy receiver system 500.

Mounted in or on the solar tower 50 is a solar energy receiver system 500, which can include one or more individual receivers. The solar receivers can be constructed to heat water and/or steam and/or supercritical steam and/or another type of heat transfer fluid using insolation received from the heliostats. Alternatively or additionally, the target or receiver 500 can include, but is not limited to, a photovoltaic assembly, a steam-generating assembly (or another assembly for heating a solid or fluid), a biological growth assembly for growing biological matter (e.g., for producing a biofuel), or any other target configured to convert focused insolation into useful energy.

The solar energy receiver system 500 can be arranged at or near the top of tower 50, as shown in FIG. 1. In another embodiment, a secondary reflector 40 can be arranged at or near the top of a tower 50, as shown in FIG. 2. The secondary reflector 40 can thus receive the insolation from the field of heliostats 60 and redirect the insolation (e.g., through reflection) toward a solar energy receiver system 500. The solar energy receiver system 500 can be arranged within the field of heliostats 60, outside of the field of heliostats 60, at or near ground level, at or near the top of another tower 50, above or below reflector 40, or elsewhere.

More than one solar tower 50 can be provided, each with a respective solar energy receiving system thereon, for example, a solar power steam system. The different solar energy receiving systems may have different functionalities. For example, one of the solar energy receiving systems may heat water using the reflected solar radiation to generate steam while another of the solar energy receiving systems may serve to superheat steam using the reflected solar radiation. The multiple solar towers 50 may share a common heliostat field 60 or have respective separate heliostat fields. Some of the heliostats may be constructed and arranged so as to alternatively direct insolation at solar energy receiving systems in different towers. In addition, the heliostats may be configured to direct insolation away from any of the towers, for example, during a dumping condition.

For example, in the embodiment of FIG. 3, two solar towers are provided, each with a respective solar energy receiving system. A first tower 50A has a first solar energy receiving system 500A while a second tower 50B has a second solar energy receiving system 500B. The solar towers 50A, 50B are arranged so as to receive reflected solar radiation from a common field of heliostats 60. At any given time, a heliostat within the field of heliostats 60 may be directed to a solar receiver of any one of the solar towers 50A, 50B. Although only two solar towers with respective solar energy receiving systems are shown in FIG. 3, any number of solar towers and solar energy receiving systems can be used.

More than one solar receiver can be provided on a solar tower. The multiple solar receivers in combination may form a part of the solar energy receiving system. The different solar receivers may have different functionalities. For example, one of the solar receivers may heat water using the reflected solar radiation to generate steam while another of the solar receivers may serve to superheat steam using the reflected solar radiation. The multiple solar receivers can be arranged at different heights on the same tower or at different locations (e.g., different faces, such as a north face, a west face, etc.) on the same tower. Some of the heliostats in field 60 may be constructed and arranged so as to alternatively direct insolation at the different solar energy receiving systems.

For example, in the embodiment of FIG. 4, two solar receivers are provided on a single tower 50. The solar energy receiving system 500 thus includes a first solar receiver 810 and a second solar receiver 820. At any given time, a heliostat 70 may be aimed at one or both of the solar receivers, or at none of the receivers. In some use scenarios, the aim of a heliostat 70 may be adjusted so as to move a centroid of the reflected beam projected at the tower 50 from one of the solar receivers (e.g., 810) to the other of the solar receivers (e.g., 820). Although only two solar receivers and a single tower are shown in FIG. 4, any number of solar towers and solar receivers can be used.

Heliostats 70 in a field 60 can be controlled through a central heliostat field control system 91, for example, as shown in FIG. 5. For example, a central heliostat field control system 91 can communicate hierarchically through a data communications network with controllers of individual heliostats. FIG. 5 illustrates a hierarchical control system 91 that includes three levels of control hierarchy, although in other implementations there can be more or fewer levels of hierarchy, and in still other implementations the entire data communications network can be without hierarchy, for example, in a distributed processing arrangement using a peer-to-peer communications protocol.

At a lowest level of control hierarchy (i.e., the level provided by heliostat controller) in the illustration there are provided programmable heliostat control systems (HCS) 65, which control the two-axis (azimuth and elevation) movements of heliostats (not shown), for example, as they track the movement of the sun. At a higher level of control hierarchy, heliostat array control systems (HACS) 92, 93 are provided, each of which controls the operation of heliostats 70 (not shown) in heliostat fields 96, 97, by communicating with programmable heliostat control systems 65 associated with those heliostats 70 through a multipoint data network 94 employing a network operating system such as CAN, Devicenet, Ethernet, or the like. At a still higher level of control hierarchy a master control system (MCS) 95 is provided which indirectly controls the operation of heliostats in heliostat fields 96, 97 by communicating with heliostat array control systems 92, 93 through network 94. Master control system 95 further controls the operation of a solar receiver (not shown) by communication through network 94 to a receiver control system (RCS) 99.

In FIG. 5, the portion of network 94 provided in heliostat field 96 can be based on copper wire or fiber optic connections, and each of the programmable heliostat control systems 65 provided in heliostat field 96 can be equipped with a wired communications adapter, as are master control system 95, heliostat array control system 92 and wired network control bus router 100, which is optionally deployed in network 94 to handle communications traffic to and among the programmable heliostat control systems 65 in heliostat field 96 more efficiently. In addition, the programmable heliostat control systems 65 provided in heliostat field 97 communicate with heliostat array control system 93 through network 94 by means of wireless communications. To this end, each of the programmable heliostat control systems 65 in heliostat field 97 is equipped with a wireless communications adapter 102, as is wireless network router 101, which is optionally deployed in network 94 to handle network traffic to and among the programmable heliostat control systems 65 in heliostat field 97 more efficiently. In addition, master control system 95 is optionally equipped with a wireless communications adapter (not shown).

The solar field can include a first set of sun-tracking assemblies (e.g., heliostats) and a second set of sun-tracking assemblies. The sun-tracking assemblies in the solar field can be operated according to a first manner in the absence of wind or during relatively light wind conditions. During strong/intense wind conditions, all of the sun-tracking assemblies can be operated according to a second manner different from the first manner. In medium/moderate wind conditions, the first set of sun-tracking assemblies can be operated according to a third manner, while the second set of sun-tracking assemblies can continue to be operated according to the first manner.

For example, sun-tracking assemblies in a particular location of the solar field can be operated in the third manner during moderate wind conditions while sun-tracking assemblies in another location of the solar field (e.g., a downwind location from the particular location) can operate in the first manner. The first manner may be a normal operating manner whereby the sun-tracking assemblies follow the sun. In contrast, the second manner may be a safety mode, whereby the sun-tracking assemblies orient to a survival or stow configuration to reduce and/or minimize the potential for wind-induced damage (e.g., by orienting the panels in a substantially horizontal orientation). In the third manner, the sun-tracking assemblies may be operated with wind-buffering orientations designed to reduce the impact of the wind on other sun-tracking assemblies.

The sun-tracking assemblies operating in the third manner may thus serve as a wind fence for the other sun-tracking assemblies. These assemblies may block (or at least reduce the intensity of wind that prevails outside of the solar field (or on the other side of the wind fence formed by the first set of assemblies) from locations where the second set of assemblies are situated. Sun-tracking assembly orientations can be determined in advance using analytical (for example, classical analysis techniques) or numerical (for example, CFD) techniques. Values of these pre-determined orientations may be stored in a computer memory (for example, simulation module 1908 in FIG. 19). When moderate-intensity winds are detected or predicted to occur, each sun-tracking assembly can be reoriented to its respective pre-determined orientation. For example, low wind intensities may be characterized by a velocity less than about 10 m/s. High wind intensities may be characterized by a velocity greater than about 14 m/s. Moderate wind intensities may be characterized by a velocity between 10 m/s and 14 m/s.

A mirror assembly, as used herein, can include one or more mirrors. FIGS. 6-9 illustrate heliostats having a single mirror; however, heliostats assemblies can also include multiple mirrors, for example, as shown in FIG. 10. The heliostat mirror assembly can include a compact heliostat 90 bearing a single mirror 102 attached to a support structure and capable of azimuth movement through a full 360° of rotation by means of azimuth movement actuator 84 mounted on a heliostat pole 150. Thus, the heliostat can have at least two degrees of freedom for panel/mirror motion: a first degree of freedom relating to the elevation angle and a second degree of freedom relating to the azimuth angle.

The sun-tracking assemblies or heliostats can be operated in a variety of modes (related to desired panel orientations) based on operating conditions, and, in particular, wind conditions. In a tracking mode, the sun-tracking assembly may track the sun. When the sun-tracking assembly is a heliostat, the heliostat 1102 tracks the sun so as to direct insolation onto a specific aiming point on the solar receiver 500 (FIG. 11), as determined for that specific heliostat by a heliostat controller. In a safe mode, the sun-tracking assembly may orient its panel surface in such a manner to minimize or at least reduce the potential for damage to the assembly. For example, the safe mode may be a substantially static position assumed when the wind is relatively strong. Such a position is shown as 1202 in FIG. 12, where the panel of the heliostat 1200 arranged substantially horizontal with the working surface (e.g., a reflective or photovoltaic surface) arranged up.

In a standby mode, the heliostat 1104 (FIG. 11) continues to track the sun, but the aiming location is away from the solar receiver 500. Such a state may allow for startup control whereby heliostats can be brought quickly into full tracking mode. In addition, it may be used during certain periods (e.g., dumping). In a sleep mode, the heliostat 1200 can be oriented at a substantially vertical orientation, as shown in 1206 in FIG. 12. The heliostat 1202 may also be slightly displaced from vertical such that the working surface (shaded surface) points slightly downward, thereby minimizing or at least reducing the likelihood of particulate accumulation on the working surface.

In a wind-buffering mode, the orientation of the heliostat panel may be different than the tracking or safe mode. In particular, the orientations may be selected so as to disrupt the wind flow and reduce the intensity of the wind downstream from the heliostat. Referring to FIG. 13, panels 1306-1308 of heliostats 1303-1305 are oriented away from a normal tracking mode so as to reduce the wind intensity detectable at heliostat 1302. Variations on the wind buffering orientations of the panels 1306-1308 are shown as dashed lines in FIG. 13. The wind intensity in the region between devices 1304-1305 is less than the wind intensity that is incident on device 1302. Similarly, the wind intensity in the region between devices 1303-1304 is less than the wind intensity in the region between devices 1304-1305 because device 1304 plays a role in reducing the wind intensity. The wind intensity at 1302 may be significantly less than the wind intensity incident upon device 1305. In FIG. 13, three sun-tracking devices are oriented in a specific wind-buffering configuration, although fewer or greater numbers of wind-buffering sun-tracking devices can be employed, according to one or more contemplated embodiments.

For example, the orientation of the panel surfaces 1306-1308 can have a staggered configuration, as illustrated in FIG. 14A. The staggered arrangement may be with respect to a direction of the wind 1400 or a radial line with respect to a center of the solar field, for example, line 1402. Such a staggered angle configuration for multiple sun-tracking devices may be especially effective for reducing wind intensity at a desired location. Additionally or alternatively, panels 1306-1308 of the wind-buffering heliostats can be controlled (e.g., by controller 91 of FIG. 5 or controller 1902 of FIG. 19) in such a manner so that the orientation adopted in response to the wind condition does not cause glint or glare situations for workers within the solar field and/or for passers-by including but not limited to humans and native wildlife. The staggered configurations may be with respect to azimuth angles (FIG. 14B), wherein panels 1306-1308 are arranged in azimuth directions 1406-1408 respectively, all of which are at an angle with respect to the wind direction 1400.

FIG. 15 illustrates a cluster 1500 of sun-tracking devices 1502 surrounding a solar tower 50. Some of the heliostats 1502 within portion 1504 of cluster/field 1500 are near the perimeter of the cluster or perimeter proximate. The heliostats in the perimeter portion 1504 may be preferentially selected for wind-buffering orientations so as to protect other heliostats 1502 within the field and closer to the tower 50. Although four perimeter portions 1504 are illustrated in the figure, greater or fewer perimeter portions, as well as variations in the size of the perimeter portions, are possible according to one or more contemplated embodiments. In addition, not all perimeter portions 1504 may be active in a wind-buffering mode at a given time. For example, the perimeter portions 1504 placed in wind-buffering mode may be selected based on wind direction or changes in wind direction. Alternatively or additionally, the perimeter portion may include one or more outermost rows of heliostats 1502, for example, the rows within circumferential region 1506. One or more heliostats 1502 within this circumferential region 1506 may be placed in a wind-buffering orientation in order to protect one or more other heliostats 1502 within an inner region 1508.

After rotating, displacing, or otherwise moving to the final wind-buffering orientation (i.e., rotating the panel from its normal sun-tracking orientation to a wind-buffering orientation), the sun-tracking assembly may remain at or near the final wind-buffering orientation for a predetermined period of time. For example, the sun-tracking assembly may remain at the wind-buffering orientation between 5 minutes and 60 minutes, greater than 60 minutes, or as long as wind conditions dictate. Movement from the normal sun-tracking mode to the wind-buffering mode may require a certain amount of transit time, for which the sun tracking device is considered en route. This en route orientation may still be useful in at least partially blocking wind and/or reducing wind intensity for at least some other sun-tracking devices or wind sensitive components.

As shown in FIG. 15, sun-tracking devices 1502 in a perimeter portion 1506 of field 1500 of sun-tracking devices 1502 can be used as the primary wind-buffering agents. The sun-tracking devices 1502 in the inner portion 1508 of the cluster 1500 thus benefit from the wind-intensity reducing services of the re-oriented sun-tracking devices in the perimeter portion 1506. In one example, at most a small percentage of sun-tracking devices within a given cluster (e.g., having at least 50, at least 200, or even greater than 1,000 devices) reorient from a normal sun-tracking mode to a wind-buffering mode in response to wind. For example, up to 20% of the sun-tracking devices of the cluster may operate in wind-buffering mode (although greater or lesser percentages may also be possible depending on cluster size, definition, and arrangement). Of those operating in wind-buffering mode, anywhere from 30% to 90% of the wind-buffering devices may be located at or near the perimeter of the cluster 1500 (e.g., in regions 1504 or 1506) of sun-tracking devices. The sun-tracking devices in the perimeter portions (e.g., 1504 or 1506 in FIG. 15) can be reinforced and/or have extra mechanical stability against the wind. Conversely, the sun-tracking devices in the inner portions (e.g., 1508) may have less mechanical stability and/or be constructed from cheaper materials.

A thickness of a perimeter-proximate region 1506 may be measured, for example, according to device rows. Even if the devices are not exactly lined up, there may be multiple discernible rows (e.g., circumferentially arranged rows) of sun-tracking devices 1502 at or near the perimeter. In some configurations, between 5 and 100 or greater sun-tracking devices 1502 may adopt wind-buffering configurations. The wind-responsive sun-tracking devices may be concentrated at or near the perimeter of the cluster 1500. For example, between 30% and 70% or greater of these wind-responsive sun-tracking devices may be in the outer-most (i.e., closest to the perimeter) row and/or second through sixth rows from the cluster perimeter.

Operation of the sun-tracking devices in the perimeter region can be based at least in part on the direction of the wind. For example, the wind intensity or wind direction may change. In the case of FIG. 16, when there is wind out of the east, the sun-tracking devices that are reoriented into wind-buffering configurations are located substantially near the eastern side of the perimeter of cluster 1600 of sun-tracking devices, i.e., regions 1604 a-1604 b. The sun-tracking devices at other portions of the perimeter region 1604 (e.g., region 1604 c near the west side) may be configured to behave like sun-tracking devices in the inner portions 1602 of cluster 1600. In other words, sun-tracking devices in the inner portions 1602 and in the perimeter portions 1604 outside of the selected wind-buffering perimeter portions 1604 a-1604 b operate in normal tracking mode to direct incident solar radiation onto the target in the solar tower 50.

Operation of the sun-tracking assemblies in response to wind can include classifying current or future wind conditions and analyzing such conditions. Any number of methods may be employed for predicting wind-conditions according to one or more contemplated embodiments. In some examples, the wind condition may be predicted according to historical data, for example, using some sort of time-series or other algorithms. Alternatively or additionally, wind conditions may be predicted according to time of day, month of the year, barometric pressure, humidity or any other input data. Wind prediction data can also be received from a third party, for example, remote from the location of the sun-tracking assemblies. The classification of wind conditions may be carried out based on a threshold value.

Wind parameters that may be monitored, and which may influence the orientation behavior of sun-tracking apparatus include but are not limited to a wind speed, wind direction (e.g., relative to a deployment geometry for one or more sun-tracking devices), a change in wind magnitude or wind direction (e.g., an absolute change, relative change, or fractional change) and a time duration for one or more wind conditions. Wind parameters may relate to measured wind parameters, predicted wind parameters or historical wind parameters. For example, there may be an assumption that future wind behavior will resemble historical wind behavior.

Reorienting heliostats into wind-buffering mode may involve a potential cost (e.g., loss of insolation harvesting, reduced time of full insolation potential, and increased energy expenditures for reorientation). For example, due to the transition time, the sun-tracking assembly might be in an orientation that is less than optimal for harvesting insolation for the particular sun-tracking assembly. Duration of the measured or predicted wind condition can be predicted. If the wind condition is predicted to last longer than a predetermined threshold time, the sun-tracking device may be re-oriented. The predetermined threshold time may take into account the amount of transit time necessary to move to the wind-buffering orientation. Alternatively or additionally, other wind conditions may be used in conjunction with anticipated duration values in determining whether to transition the heliostats to the wind-buffering orientation. For example, if a relatively strong gust is predicted to last a relatively short time, the control system may still elect to transition one or more heliostats to wind-buffering mode to avoid any potential damage or injury to other heliostats.

Although examples and embodiments presented herein have made reference to heliostats as sun-tracking assemblies, it is also readily apparent that the teaching of the present disclosure are equally applicable to other sun-tracking assemblies, such as a field of PV cells, as shown in FIG. 17. In contrast to heliostats, dual-axis PV trackers are not required to redirect solar energy to a certain target. Rather, PV tracking assemblies follow the sun so that light from the sun is incident upon the surface of the panel substantially normally thereto.

In addition, although examples and embodiments presented herein have discussed using sun-tracking assemblies to protect other sun-tracking assemblies in the solar field from wind, the wind-buffering sun-tracking assemblies can also be used to protect other wind-sensitive components in or around the solar field from wind, according to one or more contemplated embodiments. For example, FIG. 20 shows a wind-sensitive component 2006 within a solar field surrounding solar tower 50 with a target 500 therein. During certain wind conditions, a heliostat 2008 in an interior portion of the field may continue to reflect sunlight at the target 500. One or more perimeter heliostats 2002, 2004 proximal to the wind sensitive component or structure 2006 can adopt an orientation that does not track the sun to protect the wind sensitive component from the effects of the wind. Wind sensitive components/structures may include, but are not limited to, heliostat controllers, solar field maintenance apparatus, sensors or detectors, operator enclosures, and native animal habitats. Additionally, the perimeter heliostats 2002, 2004 may also serve as a wind buffer for the interior heliostat 2008, which continues to track the sun.

Sun-tracking assemblies that are intended to serve as wind buffers for other sun-tracking assemblies or for wind sensitive components may be constructed to be wind resistant, or at least more wind resistant than the other sun-tracking assemblies. Thus, as shown in FIG. 20, perimeter heliostats 2002, 2004 may be made more robust than heliostat 2008, which remains configured to track the sun. For example, heliostats 2002, 2004 may employ reinforced, stronger, and/or more expensive materials. Additionally or alternatively, heliostats 2002, 2004 may employ larger structures, for example, thicker heliostat poles or mirrors. It is also contemplated that there may be variations of sturdiness for heliostats within the field with respect to location within the field and/or anticipated wind conditions. For example, heliostat 2002, which is located more toward the perimeter of the field than heliostat 2004, may be stronger or more wind resistant than heliostat 2004, which in turn is stronger or more wind resistant than heliostat 2008.

Control of the sun-tracking assemblies to protect wind-sensitive structures or other sun-tracking assemblies can be based on wind conditions and/or wind parameters. For example, a structure 1812 located within solar field 1800 is to be protected from incoming wind gusts incident on a northern perimeter of the field 1800. Sun-tracking assemblies 1802 can be distributed in an array within field 1800, which can be separated into four quadrants based on the cardinal directions, i.e., a northeast quadrant 1804, a northwest quadrant 1806, a southwest quadrant 1808, and a southeast quadrant 1810. Depending on wind speed, wind direction, and/or changes thereof, sun-tracking assemblies 1802 in one or more of the quadrants can be reoriented to protect structure 1812. Thus, for the northerly wind gust 1814, sun-tracking assemblies 1802 in quadrants 1804 and 1806 may be operated in a wind-buffering mode to protect structure 1812. Sun-tracking assemblies 1802 in the other quadrants 1808, 1810 may continue tracking the sun normally. When the gust switches to a north-westerly direction 1816, structure 1812 can be protected by operating the sun-tracking assemblies 1802 in quadrant 1806 in a wind-buffering mode. Sun-tracking assemblies 1802 in quadrants 1804, 1808, and 1810 may operate in a normal sun-tracking mode. Of course, other field demarcations and methods for selection of wind-buffering/sun-tracking assemblies are also possible according to one or more contemplated embodiments.

Referring to FIG. 19, control of the sun-tracking assemblies 1914 may be effected by a control system 1902, which may be centralized or distributed. Control system 1902 may use any number of inputs of information/data in determining orientations of the sun-tracking assemblies 1914 for a particular mode of operation (e.g., sun-tracking or wind-buffering). For example, control system 1902 may be coupled to a wind monitoring module 1906, which can include one or more sensors for monitoring wind speed, wind direction, and/or changes thereof within or proximal to a region containing the sun-tracking assemblies 1914 or a structure to be protected. Additionally or alternatively, the wind monitoring module 1906 can obtain local wind information from a weather forecasting station or from remote monitoring stations.

Historical wind information may be stored in database 1910 and used in addition to or in place of a signal from the wind monitoring module 1906. Position data for the sun-tracking assemblies 1914, as well as for other components or structures in the field, may be stored in position database 1912. This position data may be used by the control system 1902 in determining appropriate control schemes (i.e., which assemblies to operate in wind-buffering mode and the appropriate panel orientations for wind-buffering) for the sun-tracking assemblies 1914. User input module 1904 can allow for operator input of supplemental information (e.g., if a region of a field should be controlled differently due to maintenance issues) to be used in determining assembly orientations or overriding the control system 1902 to directly control the sun-tracking assemblies.

Control system 1902 may receive simulation data, for example, CFD simulations from simulation module 1908. For example, the simulation module 1908 may provide information on the effect of wind-buffering orientations for certain wind conditions. Using the simulation data, the control system 1902 can select appropriate sun-tracking assembly orientations based on the current wind conditions (e.g., from wind monitoring module 1906) to achieve one or more desired wind-buffering results and/or system operation results. For example, the simulation data may suggest orientations for one or more of the perimeter sun-tracking assemblies such that, for a given wind speed and direction, the sun-tracking assemblies experience forces less than a predetermined threshold while maximizing insolation harvesting by all sun-tracking assemblies. As a result, insolation harvesting may be sacrificed in order to reduce the potential for damage to some of the sun-tracking assemblies 1914.

Control system 1902 may cooperate with system operation module 1916 in determining appropriate sun-tracking assembly 1914 orientations. For example, when the sun-tracking assemblies 1914 are heliostats in a solar field surrounding a solar tower, reorientation of some of the heliostats to a wind-buffering mode may result in heat flux non-uniformities on a receiver in the solar tower due to loss of the insolation from wind-buffering heliostats. System operation module 1916 and/or control system 1902 may take this non-uniformity into account, for example, by redirecting heliostats which are still in sun-tracking mode onto different aiming points on the receiver thereby compensating for the lost insolation. Alternatively or additionally, system operating parameters (i.e., other than sun-tracking assembly orientation) may be varied to compensate for the loss of insolation. When more than one tower is present, some heliostats may be re-aimed at the second tower to simultaneously serve as a wind buffer for other heliostats still aimed at the first tower. Operation may be coordinated with the system operation module 1916 to account for the redistribution of insolation between the two towers.

As noted above, the control system 1902 may be configured to control orientations of some of the sun-tracking assemblies 1914 responsively to wind condition signals from the wind monitoring module 1906 and to control orientations of others of the sun-tracking assemblies 1914 responsively to a location of the sun. History database 1910 may include sun-tracking path information based on time of day, time of year, and location in the field for each of the sun-tracking assemblies. Additionally or alternatively, control system 1902 may receive a data signal (not shown) indicating sun location and movement for the purposes of determining an appropriate sun-tracking path for each of the sun-tracking assemblies. Although shown as separate components, it is contemplated that one or more of the components of FIG. 19 may be integrated with or subsumed by others of the components of FIG. 19. For example, control system 1902 may include user input module 1904, wind monitoring module 1906, simulation module 1908, history database 1910, position database 1912, and/or system operation module 1916 as a single system.

In some embodiments, one or more of the teachings of the present disclosure may obviate the need to deploy expensive, mechanically-reinforced and/or heavier sun-tracking assemblies throughout the solar field (or limit the deployment of such assemblies to specific regions of the solar field). In addition, the teachings of the present disclosure may allow operation of sun-tracking assemblies in a substantially normal tracking mode more frequently than would otherwise occur due to moderately windy conditions. The overall solar-energy harvest efficiency may thus be increased. Moreover, the need for deploying a wind fence (e.g., a wall or other barrier surrounding the solar field) may be obviated.

In one or more embodiments, a method of heliostat operation can include responding to a wind parameter indicative of wind conditions by respectively re-orienting each of a first and second heliostat to different respective destination orientations (or different regions of orientation space) such that for at least one of the first and second heliostats, the destination orientation (or region of orientation space) is determined in accordance with at least one of (1) an inter-heliostat distance between the first and second heliostats, (2) an angle between an inter-heliostat vector and a wind direction vector, (3) relative sizes of the first and second heliostats, (4) relative heliostat-tower distances of the first and second heliostats, and (5) terrain conditions.

In an embodiment, a method of operating sun-tracking devices can include operating the sun-tracking devices of a cluster (having at least 25 devices and preferably greater than 500 devices) so that at least some sun-tracking devices of the cluster re-direct insolation to the target while tracking the sun. The method can further include responding to a wind parameter. Such a response to the wind parameter can include, for a first sub-set of the sun-tracking devices that are directing insolation to the target, reorienting the sun-tracking devices of the first sub-set away from the target. For a second sub-set of the sun-tracking devices that are directing insolation to the target, maintaining the operating whereby the sun-tracking devices of the second sub-set continue to redirect insolation to the target while tracking the sun. Such sun-tracking devices can be heliostats or solar dishes, for example.

In another embodiment, a method of operating sun-tracking devices can include operating the sun-tracking devices of a cluster (having at least 3 devices and preferably greater than 25 devices) so that at least some sun-tracking devices of the cluster are oriented so that sunlight is substantially normal to a panel thereof as the panel tracks the sun. The method can further include responding to a wind parameter. Such a response to the wind parameter can include, for a first sub-set of the sun-tracking devices that are tracking the sun, reorienting the sun-tracking devices of the first sub-set such that sunlight is not substantially normal to the panel thereof. For a second sub-set of the sun-tracking devices that are tracking the sun, maintaining the operation whereby the sun-tracking devices of the second sub-set continue to be oriented with sunlight incident substantially normal to the panel thereof as the panel tracks the sun. Such tracking devices can be PV panels, for example.

In either of the immediately aforementioned embodiments, membership of a sun-tracking device in the first sub-set may be based on location of the device with respect to other sun-tracking devices of the cluster. For example, members of the first sub-set may include a greater percentage of sun-tracking devices near the perimeter of the cluster. In another example, the method may include determining an indication of a respective distance between the sun-tracking device and a perimeter of the cluster, and determining membership for the sun-tracking device in either the first or second sub-set based on the determined distance.

In embodiments, a solar energy system can include a solar tower, a cluster of at least 25 heliostats in a solar field, and a heliostat control system. The solar tower can have a target therein. The heliostat control system can be configured to control the orientation of the heliostats so as to redirect insolation to the target while tracking the sun. In addition, the heliostat control system can be configured to respond to wind events by reorienting at least some heliostats away from the target. On average, heliostats further from the center of the cluster may be more frequently reoriented away from the target in response to wind events as compared to heliostats deeper within the cluster, which more frequently maintain their focus on the target. In an example, at least 40% of the perimeter-proximate heliostats within a region of the perimeter of the cluster may be refocused away from the target in response to a wind event.

In embodiments, sun-tracking device operation can include measuring or predicting a local wind parameter, directing the sun-tracking device to assume a normal orientation tracking movement of the sun, and responding to the local wind parameter, reorienting the sun-tracking device away from the normal orientation without regard to tracking movement of the sun. The reoriented orientation can have an elevation angle between 20° and 70° above the horizon. The reoriented orientation can be determined on the basis of at least one of wind velocity and wind direction. The reorienting can be carried out differentially for a plurality of sun-tracking devices so as to stagger panel orientations, at least in an aerial view. Alternatively or additionally, the reorienting can be carried out differentially for a plurality of sun-tracking devices so as to provide a minimum level (guaranteed degree) of wind-blocking effect based at least in part on angles between and distances between heliostats of the plurality. Such angles may be determined according to air-flow fluid mechanics simulations, for example, CFD simulations.

In embodiments, a solar system can include a solar tower and a plurality of heliostats. The plurality of heliostats can include perimeter-proximate heliostats and interior heliostats. Each of the plurality of heliostats can have a first mode where insolation is redirected to a target mounted on the solar tower while tracking the sun and a second mode where insolation is redirected a location other than the target. Each of the plurality of heliostats can be associated with a mode transition wind threshold for transitioning from the first mode to the second mode. The perimeter proximate heliostats can be associated with (i.e., programmed to have) a lower mode transition wind threshold than the interior heliostats.

For example, the perimeter proximate heliostats may switch to second mode operation when the wind speed exceeds a first threshold. This second mode operation for the perimeter proximate heliostats may be a wind buffering orientation designed to protect the inner heliostats. The inner heliostats may switch to a second mode operation when the wind speed exceeds a second threshold higher than the first. This second mode operation for the inner heliostats may be a stow orientation or protect orientation (e.g., substantially horizontal). The second mode operation for the inner heliostats may thus be operable when the wind buffering by the perimeter proximate heliostats is insufficient to protect the inner heliostats from potential wind damage.

In embodiments, a method of heliostat operation for a set of heliostats can include responding to a measured or predicted local wind parameter by causing each heliostat of the set of heliostats to respectively re-orient to a respective aiming point. For at least five different heliostats along a direction of the wind (or along a radial direction), five different aiming points are selected. Alternatively or additionally, for at least five different heliostats relatively near to each other, five different aiming points are selected. The heliostats may be considered relatively near when every heliostat of the set of heliostats is within 5 m of at least another heliostat of the set. Alternatively, the heliostats may be considered relatively near when every heliostat is at most five times a square root of the mirror assembly area of each heliostat (assuming the same mirror assembly area for each heliostat; otherwise, an average mirror assembly area may be used). Each aiming point is separated from the four other aiming points by at least 10° in elevation and/or at least 10° in azimuth.

Although substantially planar heliostats and PV cells have been specifically illustrated in the figures, the teachings of the present disclosure are also applicable to other sun-tracking assemblies, according to one or more contemplated embodiments. For example, a sun-tracking device can be a sun-tracking curved reflector with a curved reflecting or refracting surface. The surface can have a hemisphere shape, be shaped according to a major part of a hemisphere, or be shaped as an elongated partial-cylinder. The curved surface can focus insolation at one or more focus points and/or can focus insolation to any 1-D, 2-D or 3-D manifold of points. For example, a sun-tracking curved reflector can be a dish reflector. In another example, a sun-tracking curved reflector is an elongated, parabolic trough.

It will be appreciated that the modules, processes, systems, and sections described above can be implemented in hardware, hardware programmed by software, software instruction stored on a non-transitory computer readable medium or a combination of the above. A system for controlling sun-tracking assemblies can be implemented, for example, using a processor configured to execute a sequence of programmed instructions stored on a non-transitory computer readable medium. The processor can include, but is not limited to, a personal computer or workstation or other such computing system that includes a processor, microprocessor, microcontroller device, or is comprised of control logic including integrated circuits such as, for example, an Application Specific Integrated Circuit (ASIC). The instructions can be compiled from source code instructions provided in accordance with a programming language such as Java, C++, C#.net or the like. The instructions can also comprise code and data objects provided in accordance with, for example, the Visual Basic™ language, or another structured or object-oriented programming language. The sequence of programmed instructions and data associated therewith can be stored in a non-transitory computer-readable medium such as a computer memory or storage device which may be any suitable memory apparatus, such as, but not limited to read-only memory (ROM), programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), random-access memory (RAM), flash memory, disk drive and the like. Furthermore, the modules, processes, systems, and sections can be implemented as a single processor or as a distributed processor. Further, it should be appreciated that the steps mentioned above may be performed on a single or distributed processor (single and/or multi-core). Also, the processes, modules, and sub-modules described in the various figures of and for embodiments above may be distributed across multiple computers or systems or may be co-located in a single processor or system. Exemplary structural embodiment alternatives suitable for implementing the modules, sections, systems, means, or processes described herein are provided below.

The modules, processors or systems described herein can be implemented as a programmed general purpose computer, an electronic device programmed with microcode, a hard-wired analog logic circuit, software stored on a computer-readable medium or signal, an optical computing device, a networked system of electronic and/or optical devices, a special purpose computing device, an integrated circuit device, a semiconductor chip, and a software module or object stored on a computer-readable medium or signal, for example.

Embodiments of the method and system (or their sub-components or modules), may be implemented on a general-purpose computer, a special-purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit element, an ASIC or other integrated circuit, a digital signal processor, a hardwired electronic or logic circuit such as a discrete element circuit, a programmed logic circuit such as a programmable logic device (PLD), programmable logic array (PLA), field-programmable gate array (FPGA), programmable array logic (PAL) device, or the like. In general, any process capable of implementing the functions or steps described herein can be used to implement embodiments of the method, system, or a computer program product (software program stored on a non-transitory computer readable medium).

Furthermore, embodiments of the disclosed method, system, and computer program product may be readily implemented, fully or partially, in software using, for example, object or object-oriented software development environments that provide portable source code that can be used on a variety of computer platforms. Alternatively, embodiments of the disclosed method, system, and computer program product can be implemented partially or fully in hardware using, for example, standard logic circuits or a very-large-scale integration (VLSI) design. Other hardware or software can be used to implement embodiments depending on the speed and/or efficiency requirements of the systems, the particular function, and/or particular software or hardware system, microprocessor, or microcomputer being utilized. Embodiments of the method, system, and computer program product can be implemented in hardware and/or software using any known or later developed systems or structures, devices and/or software by those of ordinary skill in the applicable art from the function description provided herein and with a general basic knowledge of solar tracking and/or computer programming arts.

Moreover, embodiments of the disclosed method, system, and computer program product can be implemented in software executed on a programmed general purpose computer, a special purpose computer, a microprocessor, or the like.

Features of the disclosed embodiments may be combined, rearranged, omitted, etc., within the scope of the present disclosure to produce additional embodiments. Furthermore, certain features may sometimes be used to advantage without a corresponding use of other features.

It is, thus, apparent that there is provided, in accordance with the present disclosure, systems, methods, and devices for wind-responsive operation of sun-tracking assemblies. Many alternatives, modifications, and variations are enabled by the present disclosure. While specific embodiments have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. Accordingly, Applicant intends to embrace all such alternatives, modifications, equivalents, and variations that are within the spirit and scope of the present invention. 

1. A method of operating a plurality of sun-tracking assemblies, the method comprising: at a first time, moving the plurality of sun-tracking assemblies along respective solar tracking paths so as to follow a movement of the sun; and at a second time, redirecting a first one of the plurality of sun-tracking assemblies away from its respective solar tracking path responsively to a wind condition while continuing to move a second one of the plurality of sun-tracking assemblies along its respective solar tracking path so as to follow the movement of the sun.
 2. The method of claim 1, wherein the redirected first one of the plurality of sun-tracking assemblies is: in a perimeter portion of a field of the sun-tracking assemblies, the redirecting being such that the redirected first one buffers one or more sun-tracking assemblies in an interior portion of the field from the wind, or proximal to a wind-sensitive component, the redirecting being such that the redirected first one buffers the wind-sensitive component from the wind.
 3. (canceled)
 4. The method of claim 1, wherein the plurality of sun-tracking assemblies are in a solar field, and the method further comprising, prior to the redirecting, selecting first ones of the plurality of sun-tracking assemblies in a portion of the solar field for the redirecting based on at least one of wind direction, wind speed, and changes in wind direction or wind speed, and the selected portion is a quadrant of the solar field based on cardinal directions.
 5. (canceled)
 6. The method of claim 1, wherein the plurality of sun-tracking assemblies are: heliostats in a solar field surrounding a solar tower, and the moving is such that insolation is reflected by the heliostats toward the tower, or the one or more sun-tracking assemblies are photovoltaic panels, and the moving is such that each panel directly faces the sun.
 7. (canceled)
 8. The method of claim 1, wherein the wind condition includes one of measured or predicted wind speed, measured or predicted change in wind speed, measured or predicted wind direction, and measured or predicted change in wind direction.
 9. The method of claim 1, wherein the redirecting is responsive to wind speed exceeding a predetermined threshold.
 10. The method of claim 1, wherein, at the second time, 20% or less of the total number of the plurality of sun-tracking assemblies are redirected away from their respective solar tracking paths responsively to a wind condition while the remaining sun-tracking assemblies continue to move along their respective solar tracking paths.
 11. The method of claim 1, wherein the redirected first one of the plurality of sun-tracking assemblies: has a greater wind resistance than the second one of the plurality of sun-tracking assemblies, or the redirected first one of the plurality of sun-tracking assemblies is different in size or strength from the second one of the plurality of sun-tracking assemblies.
 12. (canceled)
 13. The method of claim 1, wherein the redirecting includes redirecting multiple first ones of the plurality of the sun-tracking assemblies away from their respective solar tracking paths, each of the redirected first ones having a different panel orientation from others of the redirected first ones, and the panel orientations of the redirected first ones are selected so as to reduce a magnitude of the wind downwind therefrom.
 14. (canceled)
 15. A method of operating a field of sun- tracking assemblies, the method comprising: reorienting a first portion of the field of sun-tracking assemblies away from respective solar tracking paths so as to buffer a second portion of the field from wind such that the second portion of the field can continue following their respective solar tracking paths, wherein the solar field includes at least 25 sun-tracking assemblies, the sun-tracking assemblies are one of heliostat reflectors and photovoltaic cells, the first portion of the field is a perimeter portion of the field, and the second portion of the field is an inner portion of the field, and the second portion of the field is downwind from the first portion of the field. 16-19. (canceled)
 20. The method of claim 15, wherein the sun-tracking assemblies in the first portion of the field are structurally more robust than the sun-tracking assemblies in the second portion of the field.
 21. The method of claim 15, wherein panels of the sun-tracking assemblies in the first portion of the field are reoriented to have a staggered orientation with respect to a direction of the wind.
 22. The method of claim 15, wherein the reorienting is based on at least one of: spacing between adjacent sun-tracking assemblies, arrangement of adjacent sun-tracking assemblies with respect to wind direction, sizes of the sun-tracking assemblies, distance of each sun-tracking assembly from a solar target, and conditions of the field terrain.
 23. The method of claim 15, wherein the reorienting includes modifying elevation angle and/or azimuth angle of a panel of one of the sun-tracking assemblies in the first portion by at least 15°.
 24. The method of claim 15, wherein said first portion comprises 20% or less of the number of sun-tracking assemblies in the field.
 25. The method of claim 15, wherein at least 30% of the first portion sun-tracking assemblies are located in a perimeter portion of the field.
 26. (canceled)
 27. A sun-tracking system comprising: a field of sun-tracking assemblies; a wind monitoring module configured to detect or predict a wind condition, which includes at least one of wind speed, wind direction, and changes in wind speed or wind direction; and a control system coupled to the wind monitoring module so as to receive a signal therefrom indicative of the wind condition, the control system being further coupled to the field of sun-tracking assemblies to direct orientations thereof, wherein the control system is configured to control orientations of the sun-tracking assemblies in a first portion of the field responsively to the wind condition signal and to control orientations of the sun-tracking assemblies in a second portion of the field responsively to a location of the sun, the control system is further configured to control the orientations of the sun-tracking assemblies in a first portion of the field responsively to a location of the sun when the wind condition is below a predetermined threshold, the first portion is a perimeter portion of the field, and the second portion is downwind from the first portion, the sun-tracking assemblies are heliostat reflectors, solar dishes, or photovoltaic cells, and the field includes at least 25 sun-tracking assemblies.
 28. The system of claim 27, further comprising a solar tower with a target therein, wherein the field of sun-tracking assemblies is configured to direct insolation at the target, the control system is configured to control the orientations of the sun-tracking assemblies in the second portion of the field so as to reflect insolation onto the target, and the target is one of a solar thermal receiver, a photovoltaic cell, or a mirror. 29-30. (canceled)
 31. The system of claim 27, wherein at least one of the sun-tracking assemblies in the first portion of the field is more sturdy than at least one of the sun-tracking assemblies in the second portion of the field. 32-38. (canceled) 